function UI(game) {
  this.ctx = game.getContext('2d');
  
  this.getWidth = function() { return game.width; };
  this.setWidth = function(w) { game.width = w; };

  this.getHeight = function() { return game.height; };
  this.setHeight = function(h) { game.height = h; };
  
  this.clear = function() {
    var tmp = this.ctx.fillStyle;
    this.ctx.fillStyle = 'rgb(255,255,255)';
    this.ctx.fillRect(0,0,this.getWidth(),this.getHeight());
    this.ctx.fillStyle = tmp;
  }

  this.drawField = function(field) {
    
  }

};
